This invention relates generally to radio frequency array antennas and more particularly to two-dimensional multibeam array antennas.
As is known in the art, it is sometimes desirable to feed a two-dimensional array of radiating antenna elements with a beam-forming network to form a number of pencil-shaped beams of radio frequency energy disposed to cover a relatively large solid angle. One known array antenna adapted to provide such pencil-shaped beams is the so-called "bootlace lens" described in an article entitled "The Bootlace Lens", Royal Radar Establishment Journal, pp. 47-57, Oct. 1958, by H. Gent. Here a number of two-dimensional beams is formed by radiating from a feed horn into a two-dimensional array of pickup horns which in turn are connected through cables of appropriate length to the array radiating elements. While such an arrangement may be useful in many applications, it is relatively large and voluminous and hence not readily adapted for applications where space and weight are at a premium such as in missile or airplane applications.